<!doctype html>
<html lang="en-US">
  <head>
    <style>
      /* styles to be added in the next listing */
    </style>
  </head>
  <body>
    <div class="grid">
      <div class="a">a</div>
      <div class="b">b</div>
      <div class="c">c</div>
      <div class="d">d</div>
      <div class="e">e</div>
      <div class="f">f</div>
    </div>
  </body>
</html>
